Hi guys,
I just joined these forums to see if anyone here knows how to do this, I’ve been playing around for a while and haven’t come up with a solution.
The first step I took obviously was to split into two mono tracks, but from there I’ve been lost.
The reason I want this btw is because I want to do some recording from a mixer but I don’t have an interface or anything to have multiple outputs.
“LCR” has become a buzz word over the past 5 years or so. As with many other fads, it is based on an old concept, then divorced from its original purpose.
The original purpose was much like M/S recording (mid-side), which is described on Wikipedia here: https://en.wikipedia.org/wiki/Joint_(audio_engineering)#M.2FS_stereo_coding
A more detailed description: http://www.uaudio.com/blog/mid-side-mic-recording/
and an “advanced” and detailed article about using the technique creatively here: http://www.soundonsound.com/sos/apr12/articles/reaper-0412.htm
The basic idea is that by separating the “side” information from the “mid” information, the stereo width can be controlled / adjusted in post production.
Note that although this technique involves 3 audio channels, they are not 3 independent audio channels. You can’t for example record a guitar, a vocal and a piano on a 2 channel recording and then isolate each sound in post production. (Well actually, it is possible to get pretty close to that using FFT processing, but the sound quality takes a bit of a bashing. See rjh-stereo-tool.ny here: https://forum.audacityteam.org/t/karaoke-rotation-panning-more/30112/1).
The more recent fad is the idea that panning only hard left, hard right and dead centre, gives a better mix (in my opinion it sounds dreadful 
especially on headphones).
Using my above mentioned tool should bring you very close to what you want.
You can duplicate the stereo track, remove the center in one track and isolate it in the other.
You can now adjust the balance between center and sides.
The processing time can be halved by do the isolation only once.
- duplicate track
- isolate the center in the second track (“inverted”).
Played together, the center will be removed.
You can now reduce the gain on either track to adjust the balance:
- decrease on first track emphases the center (mute= only center)
- decrease on second track mixes the center back in (up to the original mix).
If you want L, R and C separately (like with the first method), you’ll have to mix and render the two tracks into a new (additional) track (e.g. with ctrl-shift-m).
The first track can be removed and one of the remaining ones be inverted.
Note: the track with the center is actually dual mono, you can therefore always delete one channel.
- track dropdown menu → split to mono and delete one track.
What do you want to do with those three tracks, eventually?